Rename Closure instance field type_arguments_ to instantiator_.

runtime/vm/bootstrap_nocore.cc

Index: runtime/vm/bootstrap_nocore.cc
diff --git a/runtime/vm/bootstrap_nocore.cc b/runtime/vm/bootstrap_nocore.cc
index 74367a1d6406facda5d50df1dbd4b2e7c009d9bf..a188ae5ddbf086389443676e5cbed01b23da2ebf 100644
--- a/runtime/vm/bootstrap_nocore.cc
+++ b/runtime/vm/bootstrap_nocore.cc
@@ -47,8 +47,23 @@ void Finish(Thread* thread, bool from_kernel) {
   // instances. This allows us to just finalize function types without going
   // through the hoops of trying to compile their scope class.
   ObjectStore* object_store = thread->isolate()->object_store();
-  Class& cls = Class::Handle(thread->zone(), object_store->closure_class());
+  Zone* zone = thread->zone();
+  Class& cls = Class::Handle(zone, object_store->closure_class());
   Compiler::CompileClass(cls);
+
+#if defined(DEBUG)
+  // Verify that closure field offsets are identical in Dart and C++.
+  const Array& fields = Array::Handle(zone, cls.fields());
+  ASSERT(fields.Length() == 3);
+  Field& field = Field::Handle(zone);
+  field ^= fields.At(0);
+  ASSERT(field.Offset() == Closure::instantiator_offset());
+  field ^= fields.At(1);
+  ASSERT(field.Offset() == Closure::function_offset());
+  field ^= fields.At(2);
+  ASSERT(field.Offset() == Closure::context_offset());
+#endif  // defined(DEBUG)
+
   // Eagerly compile Bool class, bool constants are used from within compiler.
   cls = object_store->bool_class();
   Compiler::CompileClass(cls);